Keiichi Maeda

Observational Characteristics and Possible Asphericity of Over-Luminous Type Ia Supernovae (2008)

Maeda, Keiichi, Iwamoto, Koichi

A few Type Ia supernovae (SNe Ia) have been suggested to be an explosion of a super-Chandrasekhar-mass white dwarf (WD) to account for their large luminosities, requiring a large amount of 56Ni....

Supernova Nucleosynthesis and Extremely Metal-Poor Stars (2008)

Tominaga, Nozomu, Umeda, Hideyuki, Maeda, Keiichi, Iwamoto, Nobuyuki, Nomoto, Ken'ichi

We investigate hydrodynamical and nucleosynthetic properties of the jet-induced explosion of a population III $40M_\odot$ star and compare the abundance patterns of the yields with those of the...

Evolution of newly formed dust in Population III supernova remnants and its impact on the elemental composition of Population II.5 stars (2008)

Nozawa, Takaya, Kozasa, Takashi, Habe, Asao, Dwek, Eli, Umeda, Hideyuki, Tominaga, Nozomu, ...

We investigate the evolution of dust formed in Population III supernovae (SNe) by considering its transport and processing by sputtering within the SN remnants (SNRs). We find that the fates of dust...

Supernova Nucleosynthesis in the Early Universe (2008)

Tominaga, Nozomu, Umeda, Hideyuki, Maeda, Keiichi, Nomoto, Ken'ichi, Iwamoto, Nobuyuki

The first metal enrichment in the universe was made by supernova (SN) explosions of population (Pop) III stars. The trace remains in abundance patterns of extremely metal-poor (EMP) stars. We...

Subaru and Keck Observations of the Peculiar Type Ia Supernova 2006gz at Late Phases (2008)

Maeda, Keiichi, Kawabata, Koji, Li, Weidong, Tanaka, Masaomi, Mazzali, Paolo A., Hattori, Takashi, ...

Recently, a few peculiar Type Ia supernovae (SNe) that show exceptionally large peak luminosity have been discovered. Their luminosity requires more than 1 Msun of 56Ni ejected during the explosion,...

Optical Spectropolarimetry and Asphericity of Type Ic SN 2007gr (2008)

Tanaka, Masaomi, Kawabata, Koji S., Maeda, Keiichi, Hattori, Takashi, Nomoto, Ken'ichi

We present optical spectropolarimetric observations of Type Ic supernova (SN) 2007gr with Subaru telescope at 21 days after the maximum brightness (~37 days after the explosion). Non-zero...

Multi-Dimensional Simulations of Radiative Transfer in Aspherical Core-Collapse Supernovae (2008)

Tanaka, Masaomi, Maeda, Keiichi, Mazzali, Paolo A., Nomoto, Ken'ichi

We study optical radiation of aspherical supernovae (SNe) and present an approach to verify the asphericity of SNe with optical observations of extragalactic SNe. For this purpose, we have developed...

Asphericity in Supernova Explosions from Late-Time Spectroscopy (2008)

Maeda, Keiichi, Kawabata, Koji, Mazzali, Paolo A., Tanaka, Masaomi, Valenti, Stefano, Nomoto, Ken'ichi, ...

Core-collapse supernovae (CC-SNe) are the explosions that announce the death of massive stars. Some CC-SNe are linked to long-duration gamma-ray bursts (GRBs) and are highly aspherical. One important...

Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203 (2007)

Mazzali, Paolo A., Deng, Jinsong, Pian, Elena, Malesani, Daniele, Tominaga, Nozomu, Maeda, Keiichi, ...

The Gamma-Ray Burst 031203 at a redshift z=0.1055 revealed a highly reddened Type Ic Supernova, SN 2003lw, in its afterglow light. This is the third well established case of a link between a...

The evolution of the peculiar Type Ia supernova SN 2005hk over 400 days (2007)

Sahu, D. K., Tanaka, Masaomi, Anupama, G. C., Kawabata, Koji S., Maeda, Keiichi, Tominaga, Nozomu, ...

$UBVRI$ photometry and medium resolution optical spectroscopy of peculiar Type Ia supernova SN 2005hk are presented and analysed, covering the pre-maximum phase to around 400 days after explosion....

Multi-Dimensional Simulations for Early Phase Spectra of Aspherical Hypernovae: SN 1998bw and Off-Axis Hypernovae (2007)

Tanaka, Masaomi, Maeda, Keiichi, Mazzali, Paolo A., Nomoto, Ken'ichi

Early phase optical spectra of aspherical jet-like supernovae (SNe) are presented. We focus on energetic core-collapse SNe, or hypernovae. Based on hydrodynamic and nucleosynthetic models, radiative...

Hypernovae and their Gamma-Ray Bursts Connection (2007)

Nomoto, Ken'ichi, Tanaka, Masaomi, Tominaga, Nozomu, Maeda, Keiichi, Mazzali, Paolo A.

The connection between long Gamma Ray Bursts (GRBs) and Supernovae (SNe), have been established through the well observed cases of GRB980425/SN 1998bw, GRB030329/SN 2003dh and GRB031203/SN 2003lw....

Evolution of Dust in Primordial Supernova Remnants: Can Dust Grains Formed in the Ejecta Survive and be Injected into the Early Interstellar Medium? (2007)

Nozawa, Takaya, Kozasa, Takashi, Habe, Asao, Dwek, Eli, Umeda, Hideyuki, Tominaga, Nozomu, ...

We investigate the evolution of dust that formed at Population III supernova (SN) explosions and its processing through the collisions with the reverse shocks resulting from the interaction of the SN...

SN 2006aj Associated with XRF 060218 At Late Phases: Nucleosynthesis-Signature of A Neutron Star-Driven Explosion (2007)

Maeda, Keiichi, Kawabata, Koji, Tanaka, Masaomi, Nomoto, Ken'ichi, Tominaga, Nozomu, Hattori, Takashi, ...

Optical spectroscopy and photometry of SN 2006aj have been performed with the Subaru telescope at t > 200 days after GRB060218, the X-ray Flash with which it was associated. Strong nebular...

Keck and ESO-VLT View of the Symmetry of the Ejecta of the XRF/SN 2006aj (2007)

Mazzali, Paolo A., Foley, Ryan J., Deng, Jinsong, Patat, Ferdinando, Pian, Elena, Baade, Dietrich, ...

Nebular-phase spectra of SN 2006aj, which was discovered in coincidence with X-ray flash 060218, were obtained with Keck in 2006 July and the Very Large Telescope in 2006 September. At the latter...

The Connection between Gamma-Ray Bursts and Extremely Metal-Poor Stars: Black Hole-forming Supernovae with Relativistic Jets (2007)

Tominaga, Nozomu, Maeda, Keiichi, Umeda, Hideyuki, Nomoto, Ken'ichi, Tanaka, Masaomi, Iwamoto, Nobuyuki, ...

Long-duration gamma-ray bursts (GRBs) are thought to be connected to luminous and energetic supernovae (SNe), called hypernovae (HNe), resulting from the black-hole (BH) forming collapse of massive...

Chemical Abundances in the Secondary Star of the Black Hole Binary V4641 Sagittarii (SAX J1819.3-2525) (2006)

Sadakane, Kozo, Arai, Akira, Aoki, Wako, Arimoto, Nobuo, Takada-Hidai, Masahide, Ohnishi, Takashi, ...

We report on detailed spectroscopic studies performed for the secondary star in the black hole binary (micro-quasar) V4641 Sgr in order to examine its surface chemical composition and to see if its...

Nucleosynthesis Yields of Core-Collapse Supernovae and Hypernovae, and Galactic Chemical Evolution (2006)

Nomoto, Ken'ichi, Tominaga, Nozomu, Umeda, Hideyuki, Kobayashi, Chiaki, Maeda, Keiichi

We present new nucleosynthesis yields as functions of the stellar mass, metallicity, and explosion energy (corresponding to normal supernovae and Hypernovae). We apply the results to the chemical...

A neutron-star-driven X-ray flash associated with supernova SN 2006aj (2006)

Mazzali, Paolo A., Deng, Jinsong, Nomoto, Ken'ichi, Sauer, Daniel N., Pian, Elena, Tominaga, Nozomu, ...

Supernovae connected with long-duration gamma-ray bursts (GRBs) are hyper-energetic explosion resulting from the collapse of very massive stars (about 40Mo, where Mo is the mass of the Sun) stripped...

Models for the Type Ic Hypernova SN 2003lw associated with GRB 031203 (2006)

Mazzali, Paolo A., Deng, Jinsong, Pian, Elena, Malesani, Daniele, Tominaga, Nozomu, Maeda, Keiichi, ...

The Gamma-Ray Burst 031203 at a redshift z=0.1055 revealed a highly reddened Type Ic Supernova, SN 2003lw, in its afterglow light. This is the third well established case of a link between a...

3D Models for High Velocity Features in Type Ia Supernovae (2006)

Tanaka, Masaomi, Mazzali, Paolo A., Maeda, Keiichi, Nomoto, Ken'ichi

Spectral synthesis in 3-dimensional (3D) space for the earliest spectra of Type Ia supernovae (SNe Ia) is presented. In particular, the high velocity absorption features that are commonly seen at the...

The Optical/Near-Infrared Light Curves of SN 2002ap for the First 1.5 Years after Discovery (2006)

Tomita, Hiroyuki, Deng, Jinsong, Maeda, Keiichi, Yoshii, Yuzuru, Nomoto, Ken'ichi, Mazzali, Paolo A., ...

Late-time BVRIJHK photometry of the peculiar Type Ic SN 2002ap, taken between 2002 June 12 and 2003 August 29 with the MAGNUM telescope, is presented. The light curve decline rate is derived in each...

Precursors and Main-bursts of Gamma Ray Bursts in a Hypernova Scenario (2005)

Umeda, Hideyuki, Tominaga, Nozomu, Maeda, Keiichi, Nomoto, Ken'ichi

We investigate a "hypernova" model for gamma-ray bursts (GRBs), i.e., massive C+O star model with relativistic jets. In this model, non-thermal precursors can be produced by the "first" relativistic...

The first chemical enrichment in the universe and the formation of hyper metal-poor stars (2005)

Iwamoto, Nobuyuki, Umeda, Hideyuki, Tominaga, Nozomu, Nomoto, Ken'ichi, Maeda, Keiichi

The recent discovery of a hyper metal-poor (HMP) star, whose metallicity Fe/H is smaller than 1/100,000 of the solar ratio, together with one earlier HMP star, has raised a challenging question if...

Chemical Abundances in the Secondary Star of the Neutron Star Binary Centaurus X-4 (2005)

Hernández, Jonay I. González, Rebolo, Rafael, Israelian, Garik, Casares, Jorge, Maeda, Keiichi, Bonifacio, Piercarlo, ...

Using a high resolution spectrum of the secondary star in the neutron star binary {Cen X-4}, we have derived the stellar parameters and veiling caused by the accretion disk in a consistent way. We...

Signature of Electron Capture in Iron-Rich Ejecta of SN 2003du (2004)

Hoeflich, Peter, Gerardy, Christopher L., Nomoto, Kenichi, Motohara, Kentaro, Fesen, Robert A., Maeda, Keiichi, ...

Late-time near-infrared and optical spectra are presented for the normal-bright SN2003du. At about 300 days after the explosion, the emission profiles of well isolated [FeII] lines (in particular...

Dust in the Early Universe: Dust Formation in the Ejecta of Population III Supernovae (2003)

Nozawa, Takaya, Kozasa, Takashi, Umeda, Hideyuki, Maeda, Keiichi, Nomoto, Ken'ichi

We investigate the formation of dust grains in the ejecta of population III supernovae including pair--instability supernovae, applying a theory of non-- steady state nucleation and grain growth. In...

Hypernovae and their Nucleosynthesis (2002)

Nomoto, Ken'ichi, Maeda, Keiichi, Umeda, Hideyuki, Ohkubo, Takuya, Deng, Jingsong, Mazzali, Paolo

We review the characteristics of nucleosynthesis in 'Hypernovae', i.e., core-collapse supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs). The hypernova yields show the following...

Carbon Monoxide in the Type Ic SN 2000ew (2002)

Gerardy, Christopher L., Fesen, Robert A., Nomoto, Ken'ichi, Maeda, Keiichi, Hoeflich, Peter, Wheeler, J. Craig

We present K-band (1.9 -- 2.5 micron) spectra of the Type Ic SN 2000ew observed with IRCS on the Subaru Telescope. These data show the first detection of carbon monoxide (CO) emission in a Type Ic...

Hypernova Nucleosynthesis and Early Chemical Evolution (2001)

Nomoto, Ken'ichi, Maeda, Keiichi, Umeda, Hideyuki

We review the characteristics of nucleosynthesis in 'Hypernovae', i.e., supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs). The hypernova yields compared to those of ordinary...